SQLite

** This file contains the C functions that implement date and time
** functions for SQLite.  
**
** There is only one exported symbol in this file - the function
** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: date.c,v 1.83 2008/06/12 16:35:38 drh Exp $
**
** SQLite processes all times and dates as Julian Day numbers.  The
** dates and times are stored as the number of days since noon
** in Greenwich on November 24, 4714 B.C. according to the Gregorian
** calendar system. 
**
** 1970-01-01 00:00:00 is JD 2440587.5

#endif

/*
** A structure for holding a single date and time.
*/
typedef struct DateTime DateTime;
struct DateTime {
  sqlite3_int64 iJD; /* The julian day number times 86400000 */
  int Y, M, D;       /* Year, month, and day */
  int h, m;          /* Hour and minutes */
  int tz;            /* Timezone offset in minutes */
  double s;          /* Seconds */
  char validYMD;     /* True if Y,M,D are valid */
  char validHMS;     /* True if h,m,s are valid */
  char validJD;      /* True if iJD is valid */
  char validTZ;      /* True if tz is valid */
};


/*
** Convert zDate into one or more integers.  Additional arguments
** come in groups of 5 as follows:
**

    Y--;
    M += 12;
  }
  A = Y/100;
  B = 2 - A + (A/4);
  X1 = 365.25*(Y+4716);
  X2 = 30.6001*(M+1);
  p->iJD = (X1 + X2 + D + B - 1524.5)*86400000;
  p->validJD = 1;
  if( p->validHMS ){
    p->iJD += p->h*3600000 + p->m*60000 + p->s*1000;
    if( p->validTZ ){
      p->iJD -= p->tz*60000;
      p->validYMD = 0;
      p->validHMS = 0;
      p->validTZ = 0;
    }
  }
}

/*
** Set the time to the current time reported by the VFS
*/
static void setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
  double r;
  sqlite3 *db = sqlite3_context_db_handle(context);
  sqlite3OsCurrentTime(db->pVfs, &r);
  p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
  p->validJD = 1;
}

/*
** Attempt to parse the given string into a Julian Day Number.  Return
** the number of errors.
**

** as there is a year and date.
*/
static int parseDateOrTime(
  sqlite3_context *context, 
  const char *zDate, 
  DateTime *p
){

  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    setDateTimeToCurrent(context, p);
    return 0;
  }else if( sqlite3IsNumber(zDate, 0, SQLITE_UTF8) ){
    double r;
    getValue(zDate, &r);
    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
    p->validJD = 1;
    return 0;
  }
  return 1;
}

/*
** Compute the Year, Month, and Day from the julian day number.
*/
static void computeYMD(DateTime *p){
  int Z, A, B, C, D, E, X1;
  if( p->validYMD ) return;
  if( !p->validJD ){
    p->Y = 2000;
    p->M = 1;
    p->D = 1;
  }else{
    Z = (p->iJD + 43200000)/86400000;
    A = (Z - 1867216.25)/36524.25;
    A = Z + 1 + A - (A/4);
    B = A + 1524;
    C = (B - 122.1)/365.25;
    D = 365.25*C;
    E = (B-D)/30.6001;
    X1 = 30.6001*E;
    p->D = B - D - X1;
    p->M = E<14 ? E-1 : E-13;
    p->Y = p->M>2 ? C - 4716 : C - 4715;
  }
  p->validYMD = 1;
}

/*
** Compute the Hour, Minute, and Seconds from the julian day number.
*/
static void computeHMS(DateTime *p){
  int s;
  if( p->validHMS ) return;
  computeJD(p);

  s = (p->iJD + 43200000) % 86400000;
  p->s = s/1000.0;
  s = p->s;
  p->s -= s;
  p->h = s/3600;
  s -= p->h*3600;
  p->m = s/60;
  p->s += s - p->m*60;
  p->validHMS = 1;

  p->validYMD = 0;
  p->validHMS = 0;
  p->validTZ = 0;
}

#ifndef SQLITE_OMIT_LOCALTIME
/*
** Compute the difference (in milliseconds)
** between localtime and UTC (a.k.a. GMT)
** for the time value p where p is in UTC.
*/
static int localtimeOffset(DateTime *p){
  DateTime x, y;
  time_t t;
  x = *p;
  computeYMD_HMS(&x);
  if( x.Y<1971 || x.Y>=2038 ){
    x.Y = 2000;
    x.M = 1;
    x.D = 1;
    x.h = 0;
    x.m = 0;
    x.s = 0.0;
  } else {
    int s = x.s + 0.5;
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = x.iJD/1000 - 2440587.5*86400.0;
#ifdef HAVE_LOCALTIME_R
  {
    struct tm sLocal;
    localtime_r(&t, &sLocal);
    y.Y = sLocal.tm_year + 1900;
    y.M = sLocal.tm_mon + 1;
    y.D = sLocal.tm_mday;

  }
#endif
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);
  return y.iJD - x.iJD;
}
#endif /* SQLITE_OMIT_LOCALTIME */

/*
** Process a modifier to a date-time stamp.  The modifiers are
** as follows:
**

      /*    localtime
      **
      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
      ** show local time.
      */
      if( strcmp(z, "localtime")==0 ){
        computeJD(p);
        p->iJD += localtimeOffset(p);
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
      break;
    }
#endif
    case 'u': {
      /*
      **    unixepoch
      **
      ** Treat the current value of p->iJD as the number of
      ** seconds since 1970.  Convert to a real julian day number.
      */
      if( strcmp(z, "unixepoch")==0 && p->validJD ){
        p->iJD = p->iJD/86400.0 + 2440587.5*86400000.0;
        clearYMD_HMS_TZ(p);
        rc = 0;
      }else if( strcmp(z, "utc")==0 ){
        double c1;
        computeJD(p);
        c1 = localtimeOffset(p);
        p->iJD -= c1;
        clearYMD_HMS_TZ(p);
        p->iJD += c1 - localtimeOffset(p);
        rc = 0;
      }
      break;
    }
    case 'w': {
      /*
      **    weekday N
      **
      ** Move the date to the same time on the next occurrence of
      ** weekday N where 0==Sunday, 1==Monday, and so forth.  If the
      ** date is already on the appropriate weekday, this is a no-op.
      */
      if( strncmp(z, "weekday ", 8)==0 && getValue(&z[8],&r)>0
                 && (n=r)==r && n>=0 && r<7 ){
        sqlite3_int64 Z;
        computeYMD_HMS(p);
        p->validTZ = 0;
        p->validJD = 0;
        computeJD(p);
        Z = ((p->iJD + 129600000)/86400000) % 7;

        if( Z>n ) Z -= 7;
        p->iJD += (n - Z)*86400000;
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
      break;
    }
    case 's': {
      /*

        /* A modifier of the form (+|-)HH:MM:SS.FFF adds (or subtracts) the
        ** specified number of hours, minutes, seconds, and fractional seconds
        ** to the time.  The ".FFF" may be omitted.  The ":SS.FFF" may be
        ** omitted.
        */
        const char *z2 = z;
        DateTime tx;
        sqlite3_int64 day;
        if( !isdigit(*(u8*)z2) ) z2++;
        memset(&tx, 0, sizeof(tx));
        if( parseHhMmSs(z2, &tx) ) break;
        computeJD(&tx);
        tx.iJD -= 43200000;
        day = tx.iJD/86400000;
        tx.iJD -= day*86400000;
        if( z[0]=='-' ) tx.iJD = -tx.iJD;
        computeJD(p);
        clearYMD_HMS_TZ(p);
        p->iJD += tx.iJD;
        rc = 0;
        break;
      }
      z += n;
      while( isspace(*(u8*)z) ) z++;
      n = strlen(z);
      if( n>10 || n<3 ) break;
      if( z[n-1]=='s' ){ z[n-1] = 0; n--; }
      computeJD(p);
      rc = 0;
      if( n==3 && strcmp(z,"day")==0 ){
        p->iJD += r*86400000.0 + 0.5;
      }else if( n==4 && strcmp(z,"hour")==0 ){
        p->iJD += r*(86400000.0/24.0) + 0.5;
      }else if( n==6 && strcmp(z,"minute")==0 ){
        p->iJD += r*(86400000.0/(24.0*60.0)) + 0.5;
      }else if( n==6 && strcmp(z,"second")==0 ){
        p->iJD += r*(86400000.0/(24.0*60.0*60.0)) + 0.5;
      }else if( n==5 && strcmp(z,"month")==0 ){
        int x, y;
        computeYMD_HMS(p);
        p->M += r;
        x = p->M>0 ? (p->M-1)/12 : (p->M-12)/12;
        p->Y += x;
        p->M -= x*12;
        p->validJD = 0;
        computeJD(p);
        y = r;
        if( y!=r ){
          p->iJD += (r - y)*30.0*86400000.0 + 0.5;
        }
      }else if( n==4 && strcmp(z,"year")==0 ){
        computeYMD_HMS(p);
        p->Y += r;
        p->validJD = 0;
        computeJD(p);
      }else{

  sqlite3_context *context, 
  int argc, 
  sqlite3_value **argv, 
  DateTime *p
){
  int i;
  const unsigned char *z;
  int eType;
  memset(p, 0, sizeof(*p));
  if( argc==0 ){
    setDateTimeToCurrent(context, p);
  }else if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
                   || eType==SQLITE_INTEGER ){
    p->iJD = sqlite3_value_double(argv[0])*86400000.0 + 0.5;
    p->validJD = 1;
  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
    }
  }

  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  DateTime x;
  if( isDate(context, argc, argv, &x)==0 ){
    computeJD(&x);
    sqlite3_result_double(context, x.iJD/86400000.0);
  }
}

/*
**    datetime( TIMESTRING, MOD, MOD, ...)
**
** Return YYYY-MM-DD HH:MM:SS

        case 'j': {
          int nDay;             /* Number of days since 1st day of year */
          DateTime y = x;
          y.validJD = 0;
          y.M = 1;
          y.D = 1;
          computeJD(&y);
          nDay = (x.iJD - y.iJD)/86400000.0 + 0.5;
          if( zFmt[i]=='W' ){
            int wd;   /* 0=Monday, 1=Tuesday, ... 6=Sunday */
            wd = ((x.iJD+43200000)/86400000) % 7;
            sqlite3_snprintf(3, &z[j],"%02d",(nDay+7-wd)/7);
            j += 2;
          }else{
            sqlite3_snprintf(4, &z[j],"%03d",nDay+1);
            j += 3;
          }
          break;
        }
        case 'J': {
          sqlite3_snprintf(20, &z[j],"%.16g",x.iJD/86400000.0);
          j+=strlen(&z[j]);
          break;
        }
        case 'm':  sqlite3_snprintf(3, &z[j],"%02d",x.M); j+=2; break;
        case 'M':  sqlite3_snprintf(3, &z[j],"%02d",x.m); j+=2; break;
        case 's': {
          sqlite3_snprintf(30,&z[j],"%d",
                           (int)(x.iJD/1000.0 - 210866760000.0));
          j += strlen(&z[j]);
          break;
        }
        case 'S':  sqlite3_snprintf(3,&z[j],"%02d",(int)x.s); j+=2; break;
        case 'w':  z[j++] = (((x.iJD+129600000)/86400000) % 7) + '0'; break;
        case 'Y':  sqlite3_snprintf(5,&z[j],"%04d",x.Y); j+=strlen(&z[j]);break;
        default:   z[j++] = '%'; break;
      }
    }
  }
  z[j] = 0;
  sqlite3_result_text(context, z, -1,

# 2003 October 31
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing date and time functions.
#
# $Id: date.test,v 1.29 2008/06/12 16:35:39 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Skip this whole file if date and time functions are omitted
# at compile-time
#

datetest 13.5 {strftime('%Y-%m-%d %H:%M:%f', '2007-01-01 12:59:59.6')} \
  {2007-01-01 12:59:59.600}
datetest 13.6 {strftime('%Y-%m-%d %H:%M:%S', '2007-01-01 23:59:59.6')} \
  {2007-01-01 23:59:59}
datetest 13.7 {strftime('%Y-%m-%d %H:%M:%f', '2007-01-01 23:59:59.6')} \
  {2007-01-01 23:59:59.600}

# Test for issues reported by BareFeet (list.sql at tandb.com.au)
# on mailing list on 2008-06-12.
#
# Put a floating point number in the database so that we can manipulate
# raw bits using the hexio interface.
#
do_test date-14.1 {
  execsql {

    PRAGMA auto_vacuum=OFF;
    PRAGMA page_size = 1024;
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(1.1);
  }
  db close
  hexio_write test.db 2040 4142ba32bffffff9
  sqlite3 db test.db
  db eval {SELECT * FROM t1}
} {2454629.5}

# Changing the least significant byte of the floating point value between
# 00 and FF should always generate a time of either 23:59:59 or 00:00:00,
# never 24:00:00
#
for {set i 0} {$i<=255} {incr i} {
  db close
  hexio_write test.db 2047 [format %2x $i]
  sqlite3 db test.db
  do_test date-14.2.$i {

    set date [db one {SELECT datetime(x) FROM t1}]
    expr {$date eq "2008-06-12 00:00:00" || $date eq "2008-06-11 23:59:59"}
  } {1}

}
finish_test